Method of making dry yeast



UNITED STATES PATENT OFFICE.

\VILLIAM B. D. PENNIMAN, OF BALTIKORE, MARYLAND, ASSIGNOR, BY IESNE I ASSIGNMENTS T0 WHITNEY YEAST CORPORATION, OF BOSTON, MASSACHU- SE'ITS, A- CORIPORATION OF NEW YORK.

METHOD or MAKING- nnr Ymsn No Drawing. Application filed March 6, 1918,

To all whom it may concern:

Be it known that 1, WILLIAM B. D. PENNI- MAN, a citizen of the United States of America, residing in the city of Baltimore, State of Maryland, have invented certain new and useful Improvements in Methods of Making Dry Yeast, of which the following is a specification.

This invention relates to a process for making dry alcoholic yeast developed in connection with the Whitney process described in United States Patent No. 1,306,569, dated 'June 10th, 1919, the application for which.

tosupport fermentation at ordinary tem-.

peratures. Preferably about 10% of moisture is present.

To carry out this invention, I take compressed yeast Which usually contains about 20% of live yeast cells and 80% of moisture. It may and generally does also contain starch or other filler. To this material I add a further quantity of insoluble filler, as starch or flour, and soluble filler, as dextrin or the like, which will not be injurious to the yeast plant or materials. The mixture is then agitated until all the ingredients are thoroughly incorporated; 60 F. or below is a good temperature for this operation. The material is next transferred to a vacuum container and dried, preferably at a temperature sufiiciently low to check fermentation until thecontent of moisture is reduced as just described. Ten per cent. (10%) of moisture is a good avera e. The vacuum drying usually takes two "ours 'or less, the pressure being under the conditions recited less than one-half an inch of mercury. Otherwise expressed, the vacuum is preferably the highest obtainable with a commer- Speoiflcation of Letters Patent.

Serial No. 220,801.

Patented Aug. 2, 1921.

Renewed June 10, 1921. Serial No.

cial air pump. Such a vacuum has no harmful effect on the yeast cells.

In general two parts of insoluble filler, such as starch, should be used with each part of l1ve yeast cells and to this one-half part of soluble filler is added. Asthe most easily available materials for the insoluble filler, I use starch or flour, and as the soluble ingredient, glucose or dextrin. A small percentage o soluble inorganic salts, such as ammonium phos hate, potassium nitrate, and magnesium p osphate, may be added to the mixture. This assists materially in the revivification of the yeast plant. To prevent undue fermentation during drying, this is performed at a low temperature, say 50 to F., the drying period being whatever is found necessary to reduce the moisture to the small percentage requisite to the vitality ofthe yeast cells in the finished product as and under the conditions already stated.

The dried yeast as it contains only sufiicient moisture to maintain the vitality of the yeast and not enough to support putrefactive fermentation, will keep for several months, even in ordinary paper containers, and owing to the manner of drying retains a high percentage of vitality. The

cast cells are protected by the filler used. hough this does not in any way affect the action of the yeast in the dough, it makes the material readily workable, both in mixing and in. the operation of'desiccation. The

yeast when thus preserved in a dormant condition of dryness is immediately revived or revitalized when wet prior to the bread mixingland baking operation.

aving thus described my invention, what I claim and desire to secure by Letters Pat-.

ent is 1. In the process of making dry yeast the improvement which'comprises the mixing of live yeast cells which have been separated prevent rapid fermentation.

2. In the process of making dry yeast, the improvement which consists in mixing at a temperature below that most favorable to fermentation, moist. yeast cells which have been so arated from the culture with comminute filler material and morgamc salts,

and then subjecting the material to dryin in vacuo at a low temperature, around-50 to 60 F. a

3. In theprocess of making yeast, the-improvement which consists mx'mxmg at substantially 50 to 60 F.,. moist yeast cells which have been se arated. from the cul- 10 time with comminuted ller material and inol ganic salts, and then subjecting the mate- I rial todrying in vacuo at a low temperature, around 50 to 60 F.

Signed by me at Baltimore, Maryland, this 1st day of March, 1918. 

